RNA plays many important roles in cellular function. In the Central Dogma of Biology, RNA serves as a transient carrier of genetic information and as the adapter molecule that reads the code. RNA catalyzes reactions and serves in post-transcriptional gene regulation, development, and immunity. RNA also plays roles in human disease, including Praeder-Willi and myotonic dystrophy. Understanding and harnessing the power of RNA, e.g. with RNAi, antisense technology, or with therapeutic ribozymes, requires an understanding of the structures of these RNA sequences. The goals of this proposal are to (1) Automate comparative sequence analysis of RNA to determine RNA secondary structure using pairwise structure predictions from Dynalign, our algorithm that finds the secondary structure common to two sequences. Comparative sequence analysis is the gold standard for determining RNA secondary structure in the absence of a crystal structure, but is currently labor intensive and dependent on the skill of the scientist doing the comparison. With the discovery of new classes of non-coding RNA (ncRNA) sequences that function without coding message, there is a significant need for new tools to automate the determination of secondary structure. (2) Further develop our method using Dynalign for ncRNA discovery by writing a new software package called Dynafind. Our method for ncRNA discovery takes crudely aligned sequence as input and identifies putative ncRNAs on the basis of the folding free energy change of the common structure in the alignment. (3) Scan the human and yeast genomes for novel ncRNA genes using Dynafind. We will collaborate with our co-investigators, Dr. Eric Phizicky and Dr. Todd Lowe, to test the function of putative ncRNAs that we identify. This work has broad implications for human health. Improved tools for predicting RNA structure will help in the discovery of therapeutics that are either RNA or target RNA. The discovery of novel ncRNA in the human genome will contribute to our understanding of development and cellular physiology.